General relativity may create quantum physics
General relativity is the science of the very large, stars, galaxies, and the universe as a whole. Quantum physics, meanwhile, deals with…
General relativity is the science of the very large, stars, galaxies, and the universe as a whole. Quantum physics, meanwhile, deals with the tiny: atoms, subatomic particles, and, if you get things just right, larger things like superconductors, magnets, and ultra-cold states of matter like liquid Helium. The holy grail of physics has been, for quite some time, marrying the two up.
Attempts to create a consistent theory of quantum gravity in the four dimensions of three space and one time in which we live has been a series of failures and intractable mathematical problems compounded with untestable predictions and constantly moving goal posts. Worse, it has been a steady progression of ideas that go back to the early 1980s, none of which have made any real progress in the physical realm, despite thousands of papers and countless theorems proved and side problems solved.
Coming up with a new theory of quantum gravity in this crowded field is difficult to say the least but not impossible. In my latest paper, now on arxiv, I lay out my attempt.
The central premise of the theory is that the universe actually has five dimensions, not four as we believe. I have written about this idea several times before, but let me explain why.
The universe as Einstein understood it was frozen in four dimensions. Every event was already pre-determined. Quantum mechanics threw a wrench into that idea by showing that the universe contains random outcomes, ones that defy Einstein’s deterministic approach. Moreover, quantum mechanics was able to show that reality actually seemed to contain many different realities, all interacting with one another, until we measure it. Then all those realities “collapse” and disappear. This includes apparent action at a distance where distant experiments appear to “know” how each one was set up through entanglement.
Some did not like this idea and proposed that all those realities actually exist and that whenever we make a quantum measurement the universe actually splits and each outcome goes its separate way. This is called the Many Worlds Interpretation (MWI) of quantum physics.
Another way to look at that, however, is instead of splitting, the universe is simply a four dimensional instant evolving in a much larger five dimensional universe. It turns out that this idea is mathematically equivalent to the MWI.
This additional dimension is like another dimension of time and so we can’t move around in it or perceive multiple points of it at once. We evolve and change as in time, but unlike with time our history, necessarily, also changes. This suggests the potentially frightening but possible fact that the past is not fixed. How not fixed is debatable given that most of human experience doesn’t depend on the outcomes of quantum happenstance and the phenomenon of decoherence forces most quantum deviations from classical behavior into nonexistence.
In any case, that is just one piece of the puzzle. The other problem is that once you acknowledge that there is a fifth dimension, you have to account for it within the theory of spacetime, general relativity. That means you need a five dimensional, not four dimensional, description of gravity.
Such descriptions are almost as old as general relativity itself, but they were largely developed to combine gravity with electromagnetism, called Kaluza-Klein theory, and these were not useful to me. I needed, rather, something more like the type of gravity that cosmologists use to describe the evolution of the universe’s three space dimensions within time. But instead of describing the evolution of space within time, I would describe the evolution of spacetime within a fifth dimension. (I will name this dimension quantum time for convenience.)
Having developed a five dimensional general relativity as a four dimensional universe of spacetime evolving in quantum time, I still needed to show equivalence to quantum field theory, the ultimate theory of reality as we know it.
To do that, I had to show where all this randomness comes from. I could have just suggested that the universe is fundamentally random, but that seemed to be putting off the problem, so I turned to the work of Christian Beck of Queen Mary, University of London (who was kind enough to look over the paper before I submitted it). Beck has worked extensively with the equivalence between chaotic and stochastic processes. Chaotic processes are deterministic, so they aren’t actually random, but they behave like random processes when you zoom out to a large enough scale. Your random number generator in your computer may be a chaotic process. Stochastic processes, meanwhile, are truly random.
I suggested that quantum physics actually derives from a chaotic spacetime, one that behaves completely randomly at the scale of the very tiny, say, the Planck length, which is the smallest measurable length. That chaotic behavior is very uniformly random and causes us to measure random outcomes as we do in quantum physics. We already know there are chaotic solutions to Einstein’s equations, so it is plausible.
A few nifty outcomes of this approach.
The first is that the equations are completely deterministic. There is no inherent randomness, quantum or otherwise.
Quantum interpretation gets taken care of. You have dynamic history rather than many worlds. All quantum paradoxes are solved including locality, as uncertainty about the state of the universe at our point in quantum time drives these paradoxes. There is no spooky action at a distance, no wavefunction collapse, and no Schrödinger’s cat states.
A matter-like and vacuum energy-like term fall out of the equations as fifth dimensional effects of the gravitational field. These would necessarily be “dark” because gravity couples to light by bending and shifting it, not emitting it, just like dark matter and dark energy.
You also get a quantum theory of gravity based on dynamics rather than statistics, although this part needs more work to make quantum predictions.
It reduces quantum field theory down to classical physics in a higher dimension.
All of this comes from my fitting quantum field theory into general relativity instead of the other way around, which is what most researchers have tried to do.
You can see the paper here:
Chaotic deterministic quantization in a 5D general relativity
How to quantize gravity is a major outstanding open question in quantum physics. While many approaches assume…arxiv.org